Newsweek magazine yesterday admitted it had got its facts wrong on a story alleging that American military interrogators had desecrated copies of the Qur'an, after a week of protests about the article left at least 17 people dead and more than 100 injured.

The report last week, alleging that interrogators at Guantánamo Bay had flushed a copy of the Qur'an down a toilet, sparked protests across the Islamic world.

In Afghanistan at least 17 people died and more than 100 were injured in the worst street violence the country has seen since US troops ousted the Taliban in 2001. Yesterday, a council of more than 300 mullahs in the north-eastern province of Badakhshan threatened to declare holy war on America if it failed to hand the interrogators to be punished.

Protests appeared to have been sparked after the former Pakistan cricket star Imran Khan held up a copy of the article at a press conference last week and said: "This is what the US is doing, desecrating the Qur'an."

Last night he said Newsweek's admission showed it had acted in a "highly irresponsible" manner.

An attack on the governor's office in the Afghan city of Jalalabad on Tuesday spread to other cities.

On Friday three civilians and a police officer were killed in Ghazni. There have also been protests in Pakistan, Indonesia and Gaza, and Lebanon's top cleric yesterday called for an international inquiry into the allegations.

In today's edition of Newsweek, the editor, Mark Whitaker, writes: "We regret that we got any part of our story wrong, and extend our sympathies to victims of the violence and to the US soldiers caught in its midst."

International aid workers were furious. "It's unbelievable that they could get something so important so wrong," said Nick Downie of Anso, an aid agency security body whose Jalalabad offices were looted and set on fire by protesters.

A senior Afghan government official said he was relieved that the issue had been resolved, but that Newsweek should account for its mistake.

"This is a startling admission. I think a credible organisation should have really thought hard before publishing something which could be easily used and misused for violence," he said.

"It's a relief that the desecration didn't happen, or at least in the way it was reported. But what will be hard for many Afghans to swallow is how a simple mistake or a lie cost the lives of so many people."

The ferocity of the reaction in the Muslim world caught the magazine and the US government by surprise. "Westerners, including those at Newsweek, may underestimate how severely Muslims resent the American presence, especially when it in any way interferes with Islamic religious faith," the magazine concludes in an article on the protests.

The apology is the latest in a series of retractions by respected publications including USA Today and the New York Times. But while those cases have involved fabrication by individual journalists and exposed editorial shortcomings, Newsweek argues that it followed the necessary procedures before publishing its story.

The magazine goes on to relay allegations of further instances of desecration of the Qur'an by US interrogators at Guantánamo. It quotes the notes of Marc Falkoff, a New York lawyer who represents 13 Yemeni detainees at Guantánamo.

The notes claim that 23 detainees tried to hang themselves after a guard stomped on a copy of the Qur'an. It also quotes one of the lawyer's clients as saying: "Another detainee tried to kill himself after the guard took his Qur'an and threw it in the toilet."

The magazine suggests the demonstrations in part came about because of the vulnerability of the regime of the Afghan president, Hamid Karzai. Noting that he was in Europe last week and is due in the US next week, it states: "This is a good time for his enemies to make trouble."